# How the numbers work

## Counts are real totals
Each bar is its own `hitsPerPage=0` query that reads Algolia's `nbHits` for a half-open `created_at_i` range: 7 daily buckets, or 6 five-day buckets for 30 days. Buckets align to UTC midnight, so they do not overlap and they add up to the headline total.

## Exact-word matching
Algolia counts "just" and "trust" as matches for "rust" by default. Typo tolerance is turned off, so "matching stories" means stories that contain the word.

## Sample-based figures
"Most discussed", "Highest-scoring" and the engagement chart only see the 50 most recent matches and carry a "50 latest" tag. They do not cover all of Hacker News.

## Metric definitions
- Matching stories / comments: sum of `nbHits` across the buckets, with `tags=story` or `tags=comment`.
- Matching over time: one `nbHits` per bucket from `/search_by_date`. Today's bucket is partial.
- Most discussed / Highest-scoring: max `num_comments` / `points` among the 50 most recent matches.
- Busiest thread / Distinct commenters (comments mode): grouped by `story_id` / unique `author` among the 50 most recent matching comments.
- Most engaging recent stories: top 8 by points among those 50; in comments mode, threads with the most matching comments.

## Topics over time
One request per term per period. All-time uses one point per year since 2007, 10y half-years, 5y quarters, 2y and 1y months, at most 24 points per term. Counts are stories only because story counts are exact. The footer reports the latest change of leader between complete periods and each term's peak. The current partial period is dashed and excluded from the lead-change check.

## Trending keywords
Counted from the top 500 stories with 20+ points in the range. A keyword's number is how many titles mention it, not total occurrences. Stopwords and HN prefixes (Show HN, how, new) are dropped, plurals of lowercase words merge, a phrase in 3+ titles like "Claude Code" absorbs its parts when it accounts for most of their uses, and a keyword needs 3+ titles to appear. The trending view is always about stories, whatever the Stories/Comments toggle says.